GroupCollection Class
Updated: August 2009
Represents a collection of captured groups in a single match.
Assembly: System (in System.dll)
The collection is immutable (read-only) and has no public constructor. A GroupCollection object is returned by the Match.Groups property.
The collection contains one or more System.Text.RegularExpressions.Group objects. . If the match is successful, the first element in the collection contains the Group object that corresponds to the entire match. Each subsequent element represents a captured group, if the regular expression includes capturing groups. If the match is unsuccessful, the collection contains a single System.Text.RegularExpressions.Group object whose Success property is false and whose Value property equals String.Empty.
To iterate through the members of the collection, you should use the collection iteration construct provided by your language (such as foreach in C# and For Each…Next in Visual Basic) instead of retrieving the enumerator that is returned by the GetEnumerator method.
The following example uses a regular expression with capturing groups to extract information about trademarks and registered trademarks used in text. The regular expression pattern is \b(\w+?)([\u00AE\u2122]), which is interpreted as shown in the following table.
Pattern | Description |
|---|---|
\b | Look for a word boundary. |
(\w+?) | Look for one or more word characters. Together these form the trademarked name. (Note that this regular expression assumes that a trademark consists of a single word.) This is the first capturing group. |
([\u00AE\u2122]) | Look for either the ® or the ™ character. This is the second capturing group. |
For each match, the GroupCollection contains three Group objects. The first object contains the string that matches the entire regular expression. The second object, which represents the first captured group, contains the product name. The third object, which represents the second captured group, contains the trademark or registered trademark symbol.
Module Example Public Sub Main() Dim pattern As String = "\b(\w+?)([\u00AE\u2122])" Dim input As String = "Microsoft® Office Professional Edition combines several office " + _ "productivity products, including Word, Excel®, Access®, Outlook®, " + _ "PowerPoint®, and several others. Some guidelines for creating " + _ "corporate documents using these productivity tools are available " + _ "from the documents created using Silverlight™ on the corporate " + _ "intranet site." Dim matches As MatchCollection = Regex.Matches(input, pattern) For Each match As Match In matches Dim groups As GroupCollection = match.Groups Console.WriteLine("{0}: {1}", groups(2), groups(1)) Next Console.WriteLine() Console.WriteLine("Found {0} trademarks or registered trademarks.", matches.Count) End Sub End Module ' The example displays the following output: ' r: Microsoft ' r: Excel ' r: Access ' r: Outlook ' r: PowerPoint ' T: Silverlight
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The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.